Finding the Radius from the Area
(KS3, Year 7)
How to Find the Radius from the Area
Finding the radius from the area is easy.Question
What is the radius of the circle, with area 10 cm2, below?Step-by-Step:
1
Start with the formula:
Radius = √ (A⁄π)
Don't forget: √ means square root, / means ÷ and π is pi (≈ 3.14)
2
Substitute the area into the formula. In our example, A = 10.
Radius = √ (10⁄π)
Radius = √ (10 ÷ π)
Radius = √ (10 ÷ 3.14)
Radius = √ 3.18
Radius = 1.78 cm
Answer:
The radius of the circle is 1.78 cm.Interactive Widget
Here is an interactive widget to help you learn about finding the radius of a circle from its area.Worksheet
This test is printable and sendable